Microsoft on Wednesday said that pirated copies of Windows Vista will be of limited value because the operating system's integrated anti-counterfeit technology would disable the fakes in short order.

Microsoft's response was an answer to earlier reports that final code of both Windows Vista and Office 2007 had been posted to BitTorrent download sites, peer-to-peer networks, and Usenet groups. On some message forums, pirates gloated that they could side-step Vista's product activation process with "cracked" keys.

"The copies [of Vista] available for download are not final code and users should avoid unauthorized copies which could be incomplete or tampered," a Microsoft spokesperson says.

"[These] unauthorized downloads rely on the use of pre-RTM [release to manufacturing] activation keys that will be blocked using Microsoft's Software Protection Platform. Consequently, these downloads will be of limited value," the spokesperson adds.

The new authentication scheme for Vista, which Microsoft dubs Software Protection Platform, is supposed to render the operating system inoperative if it suspects a product key is bogus. Copies of the OS whose product keys have been blocked eventually drop into a barely-usable state where only the Internet Explorer browser works, and then only for an hour before its user is automatically logged off. Office 2007, meanwhile, will use a less robust anti-piracy scheme based on Windows XP's already-deployed Windows Genuine Advantage technology.

Windows Vista and Office 2007 are scheduled for availability to businesses at the end of November, and will land in retail on Jan. 30.